Fluid heat exchange installation



May 15, 1951 c. H. WOOLLEY 2,553,493

FLUID HEAT EXCHANGE INSTALLATION Filed Oct. 2, 1948 0 7 06 1! '1 11%: wI n: 86

no 6 V 84 H 54 4 74 42 Z 44- 46 2 20a V 4 5o INYENTOR Char/e5 H iIM y mATTORNEY Patented May '15, 1%53 ATENT OFFICE FLUID HEATEXCHANGEINSTALLATION Charles H. Woollen; Cranford, N. J., assignor to TheBabcock a Wilcox Company, Rockleigh, N. 3., a corporation of New JerseyApplication October 2, 1948, Serial No. 52,561

3 Claims.

. 1 v This invention relates to fluid heaters, and is particularlyconcerned with apparatus for maintaining relatively constant thetemperature of a fluid heatedby a tubular heater. The invention isparticularly concerned with a. fluid heater which is adapted forassociation with apparatus using the heated fluid in such away that itisof great importance that the temperature of that fluid be maintained ata relatively constant value, within close limits.

gls. an example of the application of ,the in Vention a high temperaturesteam generator is referred to. Experience in the field of steamgeneration, and particularly with large boilers oi. the type used instationary practice to supply steam for turbo-electricgenerators, hasdemonstrated that certain conditions are necessary in order that themaximum of practical efficiency maybe attained. Many of these conditionsare difiicult to fulfilLfand this is particularly true of themaintenance of constant superheat, or the final temperature of steam.Relatively high steam pressures must be used in such boilers, in theinterestof eiiiciency. For the turbine use otsucli high pressure steam,the steam must not] only be, superheated. to higher temperatures assteam pressures increase, but'it is of considera'ble importance that thetotal steam temperature shall. remain substantially constant This isparover a wide range of boiler loads. ticularly important in theoperation of large central power stations which are subject to dailypeak load demands.

It is also important that a superheater. "for effecting the aboveindicated result! shall be screened to a considerable extent fromfurnace radiation. One reason for this is the importance of preventingthe superheat from being too high. Such high temperatures may damageturbines or permit'the metal of the superheater tube .to be overheatedto a damaging degree. This is particularly apt to occur when steam flowis deficient or absent, as for example, when a boiler is-being startedup.

The superheater of this invention is heated mainly by convection fromfurnace gases. Such a. superheater, when designed for safe metaltemperature and desired superheat at the full boiler load, is apt to bedeficient of superheatingcapacity at frictional loads. The factors whichrequire the predetermined superheat at full load It is one this di'fii-Further objects of the invention will appear as thefollowingdescriptionproceeds.

a The nature of the invention will be. readily understood from thefollowing description when read in connection with the accompanyingdrawing which. illustrates a preferred form of ap-- paratus forattaining the desired results.

The drawing is a somewhat diagrammatic viewin the nature of a verticalsection, showing a modern high pressure steam generator in which.

a s-uperheateris incorporated in a manner teattain. the desired results.

, The drawing discloses a large combustion chamber it of rectangularcross section fired by by burners such as l2, l4, and. hi; The walls ofthis combustion chamber are delineatedlby steam generating tubes such.as It and 25} receiving heat from combustion taking place in.

the combustion chamber Hland transmitting: that heat. to water suppliedtofthe tubes from the .steam and water drum 22. The. wall tubes areconnected to this drum at their upper ends in the manner indicated inthedrawingthe wall.

tubes 2% also extending along the roof Ztof the combustion chamber to.the drum. At the base ofthe combustion chamber the steamgen banks ofhorizontally disposed tube lengths disposed transversely of thedownwardly extending gas pass rearward of the superheater section V.

Steam to be passed to the superheater flows I from the steam space ofthe drum 22 through the two banks of horizontally extending tubes 42 andM constituting the section H of the superheater. These banks of tubesare formed by return bend coils, vertically disposed and spaced apartacross the gas pass. They are series con"- nected as to steam flow, andthesteam super--' section H flows heated by the superheater Of theseSection V consists of.

3 through the tubes 46 and downwardly between the installation walls 48and 50 to an intermediate superheater header 52.

From the header 52 steam flows through the wall tubes 54 along the wall48 and then to the left along the roof section 55. It then continues toa second intermediate superheater header 55 disposed above thesuperheater section V. This section comprises flat coils and return bendtubes forming the separated banks 60 and 62. The forward tubes of thebank 60 have their upper ends directly connected to the header 56 sothat steam flows downwardly through the first several rows of the bank58, then upward directly to the cross-over tubes such as 55, and

. then through the tubes of the rear bank 62.

From the outlet tubes of this bank the steam flows to the superheateroutlet header 1i and thence to a point of use.

The gas pass 12 in which the superheater section H is disposed is spacedrearwardly of an upward projection of the right-hand wall of thecombustion chamber, the left-hand side of this gas pass being formed bythe wall 14, extending downwardly through the banks 16 and 18 ofeconomizer tubes to the position 80. The upper part of this wall issupported by the economizer outlet tubes such as 82 and 84, which extenddownwardly from the economizer outlet header 8B.

The banks It and 18 of economizer tubes are similar "to the banks 42 and44 of superheater tubes but they are longer and their left-hand portionsextend across the bypass 90. This bypass is formed between the wall 1:!and the rearward wall of the refractory construction 32. The bypass isalso continued downwardly by the walls 94, 96, and 98 to a series ofdampers Hill which, by controlling the amount of gases flowing throughthe bypass as relative to the amount of gas passing through the gas pass12, correct changes in the superheat from a desired optimum value andbring the superheat back to the latter.

The dampers I50 may also be associated with a series of dampers I02extending across the outlet of the gas pass #2.

As to the fluid flow in the banks of economizer tubes l6'i8, water issupplied to the economizer inlet header Hi4, and from that position itflows upwardly through the banks 16 and 78 of economizer tubes, throughthe outlet tubes 82 and 84 to the header 86, and then through tubularconnections such as N16 to the drum 22.

The banks of tubes 60 and 62 of the superheater "section V are disposedin a gas passage between the inclined wall H2 and an extension of theroof of the furnace 24 so that effective heat exchange conditions aremaintained as the gases have their temperature decreased in passing overthese tubes. As the temperature of the gases decrease, their volumedecreases, and the structure of the gas pass compensates for thischanging factor.

The illustrative structure minimizes draft loss by providing for asubstantially straight line flow of furnace gases from the top of thefurnace across the banks of tubes 60 and 62 of the superheater Vandacross the space or chamber H between the tubular sections 82 and 84and the superheater section V, to the inlet space indicated below theroof section 55 and just above the superheater section H. Thus, in thegas flow from the furnace over the superheater sections, there is but asingle turn andthat turn is limited to 90-.

Particles of incombustible material separated -from the furnace gases inpassing through the chamber H0 or separated from the gases proceedingthrough the bypass 90 separate from the gases and are collected in adust hopper [l4 disposed between the walls 96 and 98.

What is claimed is:

1. In a vapor generating and superheating installation, a verticallyelongated furnace, upright steam generating tubes constituting at leastparts of the walls of the furnace and a lateral furnace gas outlet atthe upper part thereof, the predominant part of the vapor generated bythe installation being generated in said wall tubes, a liquid and vapordrum to which the upper ends of the steam generating tubes areconnected, a first convection superheater including a bank of uprighttubes disposed across the path of furnace gas flow through said outlet,said superheater tubes being subjected to high temperature gases fromthe furnace and constituting the only bank of tubes attheir zonetransversely of gas flow, wall means including parts of some of saidsteam generating furnace wall tubes forming an upright gas by-passhaving its inlet communicating with the gas space immediately to therear of said superheater, means forming an upright main gas passarranged in parallel with the by-pass and extending from a gas turningspace at the top of the installation and rearwardly of said outlet, asecond superheater including a bank of horizontally extending andvertically spaced tubes extending across gas flow in the main gas pass,means conducting steam from the steam and water drum to the inlet of thesecond superheater, means conducting superheated steam from the outletof the second superheater to the first superheater, the last mentionedmeans including a plurality of tubes having portions extending along -awall of the main pass, an economizer including a bank of verticallyspaced tube sections extending across the vertical flow of gases in saidmain gas pass and also in the gas by-pass, and gas flow control meansfor variably proportioning the gas flow between the gas by-pass and themain gas pass to control superheat.

2. In a vapor generating and superheating installation, a verticallyelongated furnace, upright steam generating tubes constituting at leastparts of the walls of the furnace and a lateral furnace gas outlet atthe upper part thereof, a liquid and vapor drum to which the upper endsof the steam generating tubes are connected, a first convectionsuperheater including a bank of upright tubes disposed across the pathof furnace gas flow through said outlet, said superheater tubes beingsubjected to high temperature gases from the furnace and constitutingthe only bank of tubes in their zone transversely of gas flow, wallmeans including parts'of some of said steam generating furnace walltubes forming an upright gas by-pass having its inlet com-- municatingwith the gas space immediately to the rear of said superheater, meansforming an upright main gas pass arranged in parallel with the by-passand extending from a gas turning space at the top of the installationand rearwardly of said outlet, a second superheater including a bank ofhorizontally extending and vertically spaced tubes extending across gasflow in the main gas pass, means conducting steam from the steam andWater drum to the inlet of the second superheater, means conductingsuperheated steam from the outlet of the second superheater to the firstsuperheater, the last mentioned means including a plurality of tubeshaving portions extending along a wall of the main pass, an economizerincluding a bank of vertically spaced tube sections extending across thevertical flow of gases in said main gas pass and also in the gasby-pass, the by-pass and the main gas pass being separated by a commonwall including parts of tubes connecting the outlet of the economizer tothe drum, and gas flow control means for variably proportioning the gasflow between the gas by-pass and the main gas pass to control superheat.

3. In a vapor generating and superheating installation, a verticallyelongated furnace, upright steam generating tubes constituting at leastparts of the walls of the furnace and a lateral furnace gas outlet atthe upper part thereof, a liquid and vapor drum to which the upper endsof the steam generating tubes are connected, a first superheaterincluding a bank of tubes, wall means including parts of some of saidsteam generating furnace wall tubes forming an upright gas bypass havingits inlet beyond the superheater relative to gas flow, means forming anupright main gas pass arranged in parallel with the by-pass andextending from a gas turning space at the top of the installation andrearwardly of said furnace outlet, a second superheater including a bankof horizontally extending and vertically spaced tubes extending acrossgas flow in the main gas pass, means conducting steam from the steam andwater drum to the inlet of the second superheater, means includingoutlet tubes 6 conducting superheated steam from the outlet of thesecond superheater to the inlet of the first superheater, an economizerincluding a of vertically spaced tube sections extending across thevertical flow of gases in said main gas pass and also in the gasby-pass, said outlet tubes conducting steam from the second superheaterextending along a Wall of the main gas pass from an elevation below thatof the upper edge of the economizer, the by-pass and the main gas passbeing separated by a common wall including parts of tubes connecting theoutlet of the economizer to the drum, and gas flow control means forvariably proportioning the gas flow between the gas by-pass and the maingas pass to control superheat, the bank of tubes of the secondsuperheater extending across the main gas pass between the wallincluding said outlet tubes and the wall as sociated with the economizeroutlet tubes.

CHARLES H. WOOLLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,959,214 Osenberg May 15, 19342,217,512 Donley Oct. 8, 1940 2,242,762 Shellenberger May 29, 19412,268,726 Pourchot Jan. 6, 1942 2,427,031 Tomrney et al Sept. 9, 1947FOREIGN PATENTS Number Country Date 454,408 Germany Jan. 7, 1928 702,613France Jan. 26, 1931

